The curse of the pharaohs or the mummy's curse or the Curse of King Tut is a curse alleged to be cast upon anyone who disturbs the mummy of an ancient Egyptian, especially a pharaoh. This curse, which does not differentiate between thieves and archaeologists, is claimed to cause bad luck, illness, or death. Since the mid-20th century, many authors and documentaries have argued that the curse is 'real' in the sense of having scientifically explicable causes such as bacteria, fungi or radiation. However, the modern origins of Egyptian mummy curse tales, their development primarily in European cultures, the shift from magic to science to explain curses, and their changing uses—from condemning disturbance of the dead to entertaining horror film audiences—suggest that Egyptian curses are primarily a cultural, not scientific, phenomenon.

There are occasional instances of genuine ancient curses appearing inside or on the façade of a tomb, as in the case of the mastaba of Khentika Ikhekhi of the 6th Dynasty at Saqqara. These appear to be directed towards the ka priests to protect the tomb carefully and preserve its ritual purity rather than as a warning for potential robbers. There had been stories of curses going back to the 19th century, but they multiplied after Howard Carter's discovery of the tomb of Tutankhamun. Despite popular misconceptions, no curse was found inscribed in the Pharaoh's tomb. The evidence for curses relating to Tutankhamun is considered to be so meager that Donald B. Redford called it "unadulterated claptrap".

Curses relating to tombs are extremely rare, possibly because the idea of such desecration was unthinkable and even dangerous to record. They most frequently occur in private tombs of the Old Kingdom era. The tomb of Ankhtifi (9–10th dynasty) contains the warning: "any ruler who... shall do evil or wickedness to this coffin... may Hemen (a local deity) not accept any goods he offers, and may his heir not inherit". The tomb of Khentika Ikhekhi (6th dynasty) contains an inscription: "As for all men who shall enter this my tomb... impure... there will be judgment... an end shall be made for him... I shall seize his neck like a bird... I shall cast the fear of myself into him".

The only known pharaonic curse found from the Old Kingdom was in the Pyramid of Pepi I where one of the passages of the Pyramid Texts gives the warning to anyone who disturbs the tomb: "He who shall give his finger against this pyramid and this god's enclosure of Pepi and of his ka, he has given his finger against Horus’s Enclosure in the Cool Waters. Nephthys shall traverse for him every place of his [father] Geb. His case has been heard by the Ennead and he has nothing, he has no house. He is one accursed, he is one who eats his own body."

Curses after the Old Kingdom era are less common though more severe, sometimes invoking the ire of Thoth or the destruction of Sekhemet. Zahi Hawass quotes an example of a post-Old Kingdom curse: "Cursed be those who disturb the rest of a Pharaoh. They that shall break the seal of this tomb shall meet death by a disease that no doctor can diagnose."

Hieroglyphs were not deciphered until the early 19th century, so reports of curses before this are simply perceived bad luck associated with the handling of mummies and other artifacts from tombs. In 1699, Louis Penicher wrote an account in which he recorded how a Polish traveler bought two mummies in Alexandria and embarked on a sea journey with the mummies in the cargo hold. The traveler was alarmed by recurring visions of two specters, and the stormy seas did not abate until the mummies were thrown overboard.

Zahi Hawass recalled that, as a young archaeologist excavating at Kom Abu Billo, he had to transport several artifacts from the Greco-Roman site. He states that his cousin died on that day, that his uncle died on its first anniversary, and that on the third anniversary, his aunt died. Years later, when he excavated the tombs of the builders of the pyramids at Giza, he encountered the curse: "All people who enter this tomb who will make evil against this tomb and destroy it may the crocodile be against them in water, and snakes against them on land. May the hippopotamus be against them in water, the scorpion on land." Though claiming not to be superstitious, Hawass decided not to disturb the mummies. However, he also claims he was later involved in the removal of two child mummies from Bahariya Oasis to a museum and reported that he was haunted by the children in his dreams – a phenomenon which he claims did not stop until the mummy of the father was reunited with the children in the museum.

The idea of a mummy reviving from the dead, an essential element of many mummy curse tales, was developed in The Mummy!: Or a Tale of the Twenty-Second Century, an early work combining science fiction and horror, written by Jane C. Loudon and published anonymously in 1827. Louisa May Alcott was thought by Dominic Montserrat to have been the first to use a fully formed "mummy curse" plot in her 1869 story Lost in a Pyramid, or The Mummy's Curse, a hitherto forgotten piece of mummy fiction that he rediscovered in the late 1990s. However, two stories subsequently discovered by S. J. Wolfe, Robert Singerman and Jasmine Day – The Mummy’s Soul (Anonymous, 1862) and After Three Thousand Years (Jane G. Austin, 1868) – have similar plots, in which a female mummy takes magical revenge upon her male desecrator. Jasmine Day, therefore, argues that the modern European concept of curses is based upon an analogy between desecration of tombs and rape, interpreting early curse fiction as proto-feminist narratives authored by women. The Anonymous and Austin stories predate Alcott's piece, raising the possibility that even earlier "lost" mummy curse prototype fiction awaits rediscovery.